State Police again raided the scandal-plagued New York Racing Association yesterday, this time probing more serious allegations – that overweight jockeys were secretly allowed to ride.

About a dozen state troopers executed search warrants at Aqueduct, Belmont and Saratoga and seized records from the horsemen’s bookkeeper, as well as personal information from the jockey rooms.

“This investigation involves the integrity of the races themselves,” a law-enforcement source told The Post, contrasting the probe with an earlier investigation launched by Attorney General Eliot Spitzer.

That probe led to the indictment of two dozen NYRA employees on tax-evasion charges and a guilty plea by the NYRA itself to involvement in a tax-fraud scheme involving parimutuel clerks.

The new investigation, also brought by Spitzer’s office, involves claims that NYRA officials looked the other way when overweight jockeys showed up for their mounts.

Racehorses are normally assigned a maximum carry weight, which has a vital bearing on the betting.

If a jockey can’t make the weight, the NYRA should not allow him ride and demand that a replacement be found.

NYRA officials told Spitzer’s investigators that they were not responsible for the failure to detect overweight jockeys, the source said.

“NYRA is saying that they’re like hotels where prostitution takes place, that they don’t have any say over that,” said the source.

A longtime NYRA observer said permitting overweight jockeys to ride was a common practice in the racing industry.

Former New York City Police Commissioner Howard Safir, a security consultant hired by NYRA to help re-establish the association’s integrity in the wake of the earlier investigation, was described as playing an “important role” in the new probe.

At least one member of the NYRA board of trustees was said by the source to be “cooperating” with investigators.

Spitzer had no immediate comment.

NYRA Security Director Ken Cook said he was aware of the probe, but couldn’t comment.

He referred questions to Spitzer’s Organized Crime Task Force.

The probe is another major blow to NYRA’s hopes of winning renewal of its state-authorized exclusive racing franchise, which expires in 2007.

Several would-be competitors, including Canadian-based conglomerate Magna Entertainment Corp., are already vying for the franchise.